On Tue, 2013-09-17 at 19:32 +0200, Harald Schmalzbauer wrote: > Bezüglich Ian Lepore's Nachricht vom 17.09.2013 18:16 (localtime): > > On Tue, 2013-09-17 at 17:38 +0200, Harald Schmalzbauer wrote: > >> ... > >>> Try this patch and see what happens: > >>> > >>> ================================================================== > >>> --- umcs.c (revision 255492) > >>> +++ umcs.c (local) > >>> @@ -230,6 +230,7 @@ > >>> .bufsize = 0, /* use wMaxPacketSize */ > >>> .callback = &umcs7840_intr_callback, > >>> .if_index = 0, > >>> + .interval = 20, /* ms */ > >>> }, > >>> }; > >>> > >>> > >>> BTW: I see that the umcs driver shouldn't do synchronous control > >>> transfers from the USB interrupt transfer callback. This should be > >>> postponed into some worker thread, for example the USB explore thread. > >>> See USB audio driver for an example. > >>> > >>> --HPS > >> I tried your patch and it works as expected: IRQs decreased to ~64/s > >> when idle/disconnected. > >> > >> One interesting thing I never measured before: > >> Console connection with 115k2 via umcs and 'while ( 2>1 ) echo "---..." > >> end' results in 8000 irqs/s :-( But that's also true for the prolific > >> (uplcom). The latter just goes down to 0.0 irqs/s when idle. > >> > >> Doing the same with uart0 results in 1444irqs/s. > >> Is it by design/unavoidable that transfering the same via USB multiplies > >> by factor 5-6? > >> > >> Thanks, > >> > >> -Harry > >> > > I don't know about that chipset, but with the FTDI chips it does xfers > > in 64 byte chunks and high speed bulk data results in an astronomical > > number of interrupts (and if you go fast enough, lost data). I have > > According to ASIX product brief, MCS7840 has 512 byte buffer. Pretty > much for an UART I think, which should make 115k2 baud connections with > less than 30 transfers/s work, or am I missing something?
That's the internal buffer, it still does usb transfers in smaller chunks. Some ftdi chips have 4k onboard buffers but do 64-byte usb transfers. -- Ian _______________________________________________ freebsd-usb@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-usb To unsubscribe, send any mail to "freebsd-usb-unsubscr...@freebsd.org"
